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VL53L5CX: Entering in LP mode

Balkana
Associate

When powered with 3.6V (both AVDD and IOVDD), VL53L5CX does most of the time does not enter LP mode (via the I2C command).

At 3.5V most of the time LP mode is entered correctly, and rarely - incorrectly. 

At 3.4V, LP mode is entered always correctly.

According to the datasheet, all of these are valid combinations.

Searching in the documentation so far does not explain the results.

Could anybody shed some light on the subject (else, it will be needed to modify the hardware)?

 

 

1 ACCEPTED SOLUTION

Accepted Solutions
John E KVAM
ST Employee

In the datasheet is:

JohnEKVAM_0-1710867197982.png

this says that the max rating is 3.6.

IN the paragraph above is the line:

Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

I'm going to postulate that we set that max because we started to see failures at 3.6.

Electrically, once you get the IOVDD too high, you start seeing I2C read/write failures and it's obvious in your test, but I'm thinking lots of other read/write failures will occur that are not so obvious. 

Try to find a way to limit at least the I2C. It's tolerant down to 1.6 volts.  

 

- john


If this or any post solves your issue, please mark them as 'Accept as Solution' It really helps. And if you notice anything wrong do not hesitate to 'Report Inappropriate Content'. Someone will review it.

View solution in original post

2 REPLIES 2
John E KVAM
ST Employee

In the datasheet is:

JohnEKVAM_0-1710867197982.png

this says that the max rating is 3.6.

IN the paragraph above is the line:

Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

I'm going to postulate that we set that max because we started to see failures at 3.6.

Electrically, once you get the IOVDD too high, you start seeing I2C read/write failures and it's obvious in your test, but I'm thinking lots of other read/write failures will occur that are not so obvious. 

Try to find a way to limit at least the I2C. It's tolerant down to 1.6 volts.  

 

- john


If this or any post solves your issue, please mark them as 'Accept as Solution' It really helps. And if you notice anything wrong do not hesitate to 'Report Inappropriate Content'. Someone will review it.

Thanks a lot, John - all clear now. 

You are right, other anomalies (mainly increased consumption) are present at higher voltage, despite functionally all seems fine.

To give more details: product is powered with a single cell Li-Thionyl battery, which never exceeds 3.6V, therefore according to the datasheet - it looked fine. Now it is clear that an LDO will be needed.

Could you please advise for the voltage selection for safe operation point and least possible consumption, assuming single power supply for AVDD and IOVDD, to try to maximize the battery life.

I would like to take advantage of the feature mentioned here:

https://community.st.com/t5/imaging-sensors/vl53l5cx-ultra-lite-driver-uld-enable-disable-internal-charge/m-p/89694

So I guess maybe the best value to select is 3.3V.

 

Best regards,

Marin